Bluetooth: hci_bcm4377: Add BCM4388 support

This new variant needs a different core2_window1 and always uses
beamforming.
The BAR2 also has an offset (RAM start, presumably), so add that.

Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
[sven: rebased, updated some comments, mentioned 4388 in Kconfig]
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>